Three-dimensional structure, and method and device for producing the same

ABSTRACT

A three-dimensional structure, and a method and device for producing the structure, where the structure has pressure resistant characteristics despite its voluminous and elastic nature and has higher resistance to surface wear and mechanical dimensional stability than a foamed polyethylene sheet. The three-dimensional structure is characterized in that a resin sheet has needle-like projections on its both faces, each projection has a height (H) of 3 mm or more, the height (H) and a width (W) of the projection at the height of H/2 has a relationship of H≧2.5 W, the projection has a hole in its tip, and the projections are joined to a sheet-like object at their tops. The method of producing the three-dimensional structure is characterized in that a large number of needle-like dies are integrated with a base plate, and a pair of the base plates are arranged so as to be opposed to each other, and a resin sheet is deformed when the pair of the base plates move parallel to each other so as to intrude into the resin sheet. Further, a method of continuously producing the three-dimensional structure is provided.

FIELD OF THE INVENTION

The present invention relates to a three-dimensional structure made froma resin and a method for the manufacture thereof, and more particularlyto a three-dimensional structure that excels in pressure resistancedespite having flexibility and also has water permeability and thermalinsulation properties and to a method and apparatus capable ofmanufacturing such a three-dimensional structure in an easy manner andwith good productivity.

BACKGROUND OF THE INVENTION

A variety of three-dimensional structures having protrusions formed onboth sides of a resin sheet have been suggested (JP-B-S62-15330,JP-B-H5-12139, etc.). However, the suggested structures have a highrigidity; in particular those with a thickness (height ofthree-dimensional structure) exceeding 6 mm, cannot be wound into largerolls, and are unsuitable for applications in the form of sheetmaterials that are effective when a large surface area is needed. In thestructure with both side protrusions described in JP-B-S62-15330,because the tip portions of the protrusions are flat and portionsthereof are not deformed, the thickness is large, no contribution ismade to increasing the compressive strength, and an unnecessarily largeamount of valuable resources are used. Moreover, when the structure isthermally melted to joint to other sheets, a large amount of thermalenergy is needed for melting. The resultant drawback is that thinportions on the protruding side surfaces are deformed by this extraheat. Yet another undesirable feature of the structure with flat tipportions, which is described in the aforementioned reference, is thatbecause the compressive strength increases with the number ofprotrusions, the number of protrusions cannot be increased. Moreover,because the tip portions of protrusions are flat, the flexibility of thestructure is lost accordingly.

Manufacturing a three-dimensional structure with protrusions on bothsides from a resin sheet with both side embossed rolls, as suggested inJP-B-H5-12139, requires a pulling-out angle. Therefore, the moldingprocess places limitations on the pitch and height of the projectionsobtained by embossing and a structure with high needle-like protrusionscannot be obtained with a small pitch. Furthermore, needle-likeprotrusions can be also manufactured by electric discharge processing(JP-A-2000-17091), but the absolute height of the peaks cannot beincreased. Furthermore, because only one surface can be processed in onecycle of processing, a structure with protrusions on both sides isdifficult to manufacture. A resin three-dimensional structure withprotrusions on both sides can be also manufactured by injection moldingwith dies, but because the moldings have to be pulled out from the dies,deep valleys cannot be manufactured. Moreover, the resin sometimescannot be processed to obtain thin sections of the tips, continuoussheets cannot be molded, die manufacturing cost is high due to a complexshape, and the production cost becomes high.

Furthermore, foamed sheets from polyethylene resin are used as flexiblebulky structures, but the sheets foamed to high bulkiness have a lowcompressive strength, poor water permeability, low resistance to surfacewear, and poor mechanical dimensional stability. Therefore, there is aneed for a flexible and bulky material that is air and liquid permeableand has a high compressive strength and good mechanical dimensionalstability. Furthermore, even with foamed polyethylene sheets, a productwith a thickness of 5 mm or more is technologically difficult toproduce, therefore sheets with such a thickness are obtained by joiningtogether thick foamed sheets. However, in this case, the amount of workis doubled and because cooling the intermediate sections in the joiningprocess requires time and the line speed is low, the productionefficiency is poor.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The present invention was created to overcome the above-describeddrawbacks of the conventional technology and it is an object thereof toprovide a three-dimensional structure that has pressure resistancecapability despite being bulky and flexibility, and a method for themanufacture of such a three-dimensional structure. It is another objectof the present invention to provide a method enabling the continuous andlow-cost manufacture of the three-dimensional structure in accordancewith the present invention and an apparatus therefore. Yet anotherobject of the present invention is to provide a bulky sheet havingsurface friction resistance and mechanical dimensional stability,despite having large bulkiness and thermal insulation properties, thissheet having properties superior to those of foamed sheets. It is stillanother object of the present invention to provide a filter, a drainagematerial, a thermally insulating material, and a buffer material thatare air permeable, water permeable, and flexible, but also havecompressive strength and mechanical dimensional stability.

Means to Solve the Problems

The present invention was created to attain the above-described objects,and the features of the three-dimensional structure according to thepresent invention are described below. The present invention relates toa three-dimensional structure in which needle-like protrusions formed bydeforming parts of a resin sheet are present on both sides of the resinsheet, the height H of the protrusions is 3 mm or more, and the width Wat ½ H is H>2.5 W. The present invention also relates to athree-dimensional structure, wherein the cross section of the tips ofthe needle-like protrusions has a curve with a curvature radius of 5 mmor less. The present invention also relates to a three-dimensionalstructure, wherein the tip of each needle-like protrusion is flat. Thepresent invention also relates to a three-dimensional structure, whereina hole is present in the tip of the needle-like protrusions. The presentinvention also relates to a three-dimensional structure, whereinsheet-like objects are joined to the tips of the needle-likeprotrusions. Furthermore, the present invention also relates to a filteror drainage material, wherein cavities in the three-dimensionalstructure are filled with fibrous substance.

The features of the manufacturing method according to the presentinvention are described below. The present invention relates to a methodfor the manufacture of a three-dimensional structure, wherein a pair ofsubstrates having integrated therewith multiple needle-like dies with aprotrusion height h of 3 mm or more and a width w at ½ h such that h>3 ware disposed opposite each other so as to face a resin sheet havingflowability at a deflection temperature under load of the resin or aboveit, the resin sheet is deformed by moving the needle-like dies of thepair of substrates parallel to each other so as to thrust the resinsheet, and the sheet is cooled or solidified, while maintaining thedeformed state thereof. The present invention also relates to a methodfor the manufacture of a three-dimensional structure, wherein amultiplicity of the substrates are linked together and fixed tocontinuously circulating conveyors, a pair of the conveyors are disposedopposite each other, the resin sheet heated to a temperature equal to orhigher than the deflection temperature under load is continuouslyinserted between a pair of continuously circulating conveyors, andprotrusions are formed on both sides of the resin sheet by causing thepairs of needle-like dies to thrust the resin sheet with a mechanism formoving the substrates in the direction perpendicular to the resin sheet.Furthermore, the present invention also relates to a method for themanufacture of a three-dimensional structure, wherein the tips of theneedle-like protrusions provided on both sides of the three-dimensionalstructure are pressed against a heating roll to form a hole in each tipof the needle-like protrusions.

The features of the manufacturing apparatus according to the presentinvention are described below. The present invention relates to anapparatus for the manufacture of a three-dimensional structure, soconfigured that the conveyors comprise caterpillars, the substrates arefixed to vertical pins standing on the caterpillars, and the verticalmovement is carried out by guiding the substrate support pins providedon the surface of the substrate with a grooved cam. The presentinvention also relates to an apparatus for the manufacture of athree-dimensional structure, so configured that separation plates areprovided on the surface of the substrates and the substrates and themolded resin sheet are continuously separated by guiding the separationplate support pins provided on the side surface of the separation plateswith a grooved cam. The present invention also relates to an apparatusfor the manufacture of a three-dimensional structure, so configured thatpins are provided in a vertical condition on the conveyors, thesubstrates are fixed to the conveyors by passing the pins into holesprovided in the substrates, and the vertical movement of the substratesis carried out with stands provided on both side surfaces of theconveyors.

A specific feature of the present invention is that needle-likeprotrusions are formed on both sides of a resin sheet. Thermoplasticresin, for example, polyolefine such as polyethylene and polypropylene,polycarbonate, polyamide resin such as Nylon 6 and Nylon 66, polyestersuch as polyethylene terephthalate and polybutylene terephthalate, vinylresin such as polyvinyl chloride, polystyrene resin, acrylic resin suchas methyl acrylate resin, fluorocarbon resin such astetrafluoroethylene, and a polyvinyl alcohol can be advantageously usedas the aforementioned resin. A thermosetting resin such as epoxy resin,phenolic resin, and urea resin can be used, provided it has flowabilityat temperature equal to or above the below-described deflectiontemperature under load. Furthermore, those resins can be used not onlyindividually, but also after they are combined together, e.g., byblending, or after an additive such as plasticizer, filler, antioxidant,stabilizer, and lubricant is added thereto. When the present inventionis used for civil engineering, degradable resins, for example,biodegradable resins such as polylactic acid-based resins orpolybutylene succinate or photodecomposable resins such as vinyl ketonepolymers are preferred. The present invention can also provide a softthree-dimensional structure and thermoplastic elastomers such as SBS andpolyurethanes can be also used.

In accordance with the present invention, needle-like protrusions formedby deforming parts of a resin sheet are present. The “sheet” as referredto herein is obtained by forming the resin so that it assumes asheet-like shape. No specific limitation is placed on the sheetthickness and the term “sheet” also includes the products usually calledfilms or membranes, but the thickness is preferably 10 μm or more to 2mm or less, more preferably 50 μm or more to 1 mm or less, and mostpreferably 100 μm or more to 0.5 mm or less. This is because stablemolding is difficult when the thickness is less than 10 μm or more than2 mm.

The present invention features a three-dimensional structure in whichneedle-like protrusions formed by deforming parts of a resin sheet arepresent on both sides of the resin sheet. The presence of protrusions onboth sides can increase bulkiness and provide a structure with largecavities and also to provide a structure with good thermal insulationproperties. Furthermore, the presence of protrusions on both sides alsoincreases flexibility. Another advantage of the structures havingprotrusions on both sides is that when such structures are rolled intolarge rolls, the protrusions of the upper layer and the protrusions ofthe lower layer can penetrate between the protrusions of the oppositelayer. Therefore, even though one layer has a large thickness, a compactroll can be obtained. Moreover, because the structure has front-backsymmetry, no warping occurs even when, e.g., resin sheets are joined toboth sides. The three-dimensional structure as referred to herein meansa spatial structure having protrusions on both sides of a flatsheet-like object.

A specific feature of the needle-like protrusions in accordance with thepresent invention is that the height H thereof is 3 mm or more. Theheight H of the protrusions is 3 mm or more to preferably 200 mm orless, more preferably 5 mm or more to 100 mm or less, and mostpreferably 8 mm or more to 50 mm or less. When the thickness is lessthan 3 mm, the bulkiness required for the three-dimensional structure inaccordance with the present invention cannot be attained, and when theheight is more than 200 mm, long thin protrusions by the presentinvention are sometimes difficult to manufacture with good stability.Therefore, because the three-dimensional structure by the presentinvention has protrusions on both sides, a structure having a thicknessof at least 6 mm can be obtained. Furthermore, the width W in a positionat half of the height H of the protrusions in accordance with thepresent invention satisfies the condition H>2.5 W. The capability ofincreasing the height H with respect to W is a specific feature of thepresent invention. The width W satisfies the condition H>2.5 W andpreferably H<100 W, more preferably H>3 W to H<70 W, and most preferablyH>5 W to H<50 W. Those ranges are selected because a structure withincreased bulkiness and cavity ratio and also good flexibility can beobtained. When H<2.5 W, the bulkiness required for the three-dimensionalstructure in accordance with the present invention cannot be obtained,and when H>100 W, long thin protrusions in accordance with the presentinvention are sometimes difficult to manufacture with good stability.The term protrusions do not necessarily mean only conical symmetricalshape, and the cross section in the width W direction can be of avariety of shapes, including elliptical, quadrangular, or triangularshapes. In those cases, the smallest width in the cross section at ½ His used as the value of W. Furthermore, H and W are found by measuringthe protrusions in randomly selected 30 points and finding an arithmeticaverage. The above-described requirements relating to athree-dimensional structure are the requirements relating to a “product”and all the above-described requirements are not necessarily applicableto the products manufactured by the below described manufacturing methodor manufacturing apparatus.

The number of the needle-like protrusions employed by the presentinvention mainly depends on the value of W employed in accordance withthe present invention, and a specific feature of the present inventionis that a large number of the needle-like protrusions can be providedbecause W is less than the height of the protrusions. A large number ofneedle-like protrusions mean an accordingly high compressive strength,and a small W and a large H mean a high flexibility. Therefore, thethree-dimensional structure in accordance with the present invention isa flexible structure that has a high compressive strength.

A specific feature of the three-dimensional structure in accordance withthe present invention is that the tips of the needle-like protrusionshave a curved surface and the cross section thereof preferably has acurve with a curvature radius of 5 mm or less, more preferably 0.01 mmto 2 mm, and most preferably 0.1 mm to 1 mm. With the curvature radiusmore than 5 mm, the deformation of the tip portions is insufficient, theprotrusions are too thick, and flexibility is most often insufficient.When the curvature radius of the tip portions is 5 mm or less, the tipportions can be deformed, excess thickness of the tip portions isreduced, and surface area of the tip portions is decreased, therebyincreasing flexibility. Furthermore, the reduction in the surface areaof the tip portions makes it possible to increase the number ofprotrusion.

The tips of the needle-like protrusions in the three-dimensionalstructure in accordance with the present invention also can be flat. Theflat tips may be formed in the molding process, but flattening can bealso carried out by heating and pressing the tips after thethree-dimensional structure has been molded. For example, in the casewhere the three-dimensional structure in accordance with the presentinvention is adhesively joined to other sheets, forming flat tipssometimes can be expected to increase the joining strength due toincreased joining area. The flat portions may have the same thickness asthe starting resin sheet, but it is preferred that the thickness bechanged so as to be less than the thickness of the original resin sheet.

The three-dimensional structure in accordance with the present inventioncan have a structure in which holes are present in the tip portions ofthe needle-like protrusions. In accordance with the present invention,because the needle-like protrusions are present on both sides, thestructure has high air and water permeability in the in-plane direction,but air and water permeability are sometimes required in the directionthrough the plane. Providing holes in the tip portions of theneedle-like protrusions ensures such air and water permeability in thedirection through the plane. Furthermore, a porous three-dimensionalstructure with a specific configuration that has not heretofore beenknown can be obtained. Thus, a filtering function can be provided bypassing the air or water through the structure in accordance with thepresent invention in which spaces of the protrusions are filled with afibrous substance or filler and a multilayer configuration is obtained.Moreover, if a reaction enhancer is provided in or a catalytic action isimparted to the fibrous substance or filler, the structure in accordancewith the present invention can be also used in a reaction tank such as apurification tank for contaminated water. The advantage of such astructure is that the reaction time can be shortened. No specificlimitation is placed on the shape and size of the aforementioned holesand they can be determined according to application.

A mechanical piercing method, means for heating only the tip portions,e.g., with rolls heated to a high temperature, in a state in which thetip portions are deformed with needle-like dies of an apparatus, and amethod of forming resin protrusion and then slicing out only the tipsections can be used to produce the holes in the tips of the needle-likeprotrusions. When rolls heated to high temperature are used, the rolltemperature is preferably equal to or higher than the melting point ofthe resin sheet or the glass transition temperature when noncrystallineresin is employed. It is even more preferred that the roll temperaturebe equal to or higher than the thermal decomposition temperature of theresin.

The three-dimensional structure in accordance with the present inventioncan be a structure in which sheet-like objects are joined to the tips ofthe needle-like protrusions. Thermal insulation capability can beprovided by spaces formed inside the layered configuration of thestructure and sheets. Furthermore, dimensional stability is improved andbecause movement of needle-like protrusions in the lateral direction isinhibited, the compressive strength is also increased. Sheet-likesubstances to be joined to the three-dimensional structure are notlimited to the resin sheets identical to the sheet for forming thethree-dimensional structure in accordance with the present invention andcan be a material having air and water permeability such as cloth,knitted material, nonwoven fabric, net, and paper or metal, e.g.,aluminum foil, or ceramic sheet when heat resistance is required. Aperforated film can be advantageously used for the resin sheet when airor water permeability is required. Joining an air-permeable sheet makesit possible to obtain the so-called “breathing thermally-insulatingboard”. Furthermore, using material that passes practically no air, butcan be permeated by water vapors makes it possible to obtain athree-dimensional structure having dew condensation prevention ability.As a result, the prickly feeling such as demonstrated by glass wool isprevented and the product can be reused as resin. Therefore, theenvironmental burden is low. As an example of joining methods suitablefor above-described cases, when a resin sheet is employed, it can beheated and melted and then brought into contact with the tips of theneedle-like protrusions of the three-dimensional structure and the tipportions of the needle-like protrusions can be melted by heat capacityof the melted resin sheet and joined. Furthermore, joining and adhesivebonding can be also conducted after applying an adhesive such as ahot-melt adhesive or an emulsion adhesive to the sheet-like object ortips of the three-dimensional structure.

Filling the cavities of the three-dimensional structure in accordancewith the present invention makes it possible to obtain a structurehaving a function of a filter or drainage material. Because thethree-dimensional structure in accordance with the present invention haslarge cavities and a high compressive strength, filling the cavitieswith a fibrous substance to a low filling density makes it possible toobtain a filter or drainage material with a small loss of air or waterpermeability. In this case, a structure in which sheet-like objects arejoined to the tips of the needle-like protrusions is especiallypreferred.

The three-dimensional structure in accordance with the present inventioncan be manufactured, for example, by disposing a pair of substrateshaving integrated therewith multiple needle-like dies so that thesubstrates are opposite each other and face a resin sheet that is at adeflection temperature under load of the resin or above it and,therefore, has flowability, deforming the resin sheet by moving theneedle-like dies of the pair of substrates parallel to each other so asto thrust the resin sheet, and cooling or solidifying, while maintainingthe deformed state. The deflection temperature under load of the resinis determined according to JIS K7207; it is also called a “thermaldeformation temperature”. The deflection temperature under load asemployed in accordance with the present invention is determined by a Bmethod, that is, a method in which a bending stress applied to a sampleis 45.1 N/cm2. When the temperature of the resin sheet is equal to orhigher than the resin deflection temperature under load, the resin sheetcan be deformed to obtain the needle-like protrusions. The temperatureof the resin sheet is preferably 30° C. or more, more preferably 50° C.or more, and most preferably 80° C. or higher than the deflectiontemperature under load. The deformation is possible even when thedeflection temperature under load is not reached, but in this case thedeformation takes long time and productivity is poor. Resin sheets aresometimes softened not by thermal effects, but by chemical softening,e.g., with aqueous solvent in the case of polyvinyl alcohol or withsolvent and plasticizer, as in the case of plasticizers in polyvinylchloride resins, but in those cases, the resin sheet is also required tobe at temperature equal to or higher than the deflection temperatureunder load.

The needle-like dies for deforming the resin sheet in the manufacturingmethod in accordance with the present invention preferably has aprotrusion height h of 3 mm or more and a width w at ½ h such that h>3w. Such a shape of the needle-like dies makes it possible to realizethin elongated needle-like protrusions and to obtain a three-dimensionalstructure in accordance with the present invention that is flexible, butalso has pressure resistance. The needle-like dies have a height of 3 mmor more to preferably 200 mm and less, more preferably 5 mm or more to100 mm or less, and most preferably 8 mm or more to 50 mm or less. Whenthe height is less than 3 mm, sufficient bulkiness of thethree-dimensional structure in accordance with the present inventioncannot be obtained, and when it is more than 200 mm, long thinprotrusions in accordance with the present invention are sometimesdifficult to manufacture with good stability. Furthermore, the width win a position at ½ the height h of the needle-like dies is such that h>3w, preferably to h<100 w, more preferably h>5 w to h<70 w, and mostpreferably h>10 w to h<50 w. Those ranges are selected because astructure with increased bulkiness and cavity ratio and also goodflexibility can be obtained. When h<3 w, the bulkiness required for thethree-dimensional structure in accordance with the present inventioncannot be obtained, and when h>100 w, long thin protrusions inaccordance with the present invention are sometimes difficult tomanufacture with good stability. The term “needle-like dies” does notnecessarily mean only conical symmetrical shape, and the cross sectionin the width w direction can be of a variety of shapes includingelliptical, quadrangular, or triangular shapes. In those cases, thesmallest width in the cross section at ½ h is used as the value of w.Furthermore, h and w are found by measuring the protrusions in randomlyselected 30 points and finding an arithmetic average.

Multiple needle-like dies in accordance with the present invention areintegrated with substrates. The integration may be attained byintegrally mechanically processing them of the same workpiece, but theneedle-like dies may be also joined to the substrate with various meanssuch as screwing, welding, and adhesive bonding. One more advantage ofthe thin long needle-like dies in the manufacturing method in accordancewith the present invention is that when the multiple needle-like diesare disposed in pairs opposite each other, no mechanical accuracy isrequired between the needle-like dies facing each other. The testresults confirmed that when the needle-like dies of a pair of substratesmove parallels each other so as to thrust the resin sheet; they thrustthe resin sheet, without interference between the needle-like diesfacing each other. Yet another advantage of the thin long needle-likedies in accordance with the present invention is that because they havea needle-like shape, both the thin long needle-like dies of theapparatus and the needle-like protrusions of the product demonstrategood cooling effect due to low thermal capacity thereof and theproductivity is high. Furthermore, not only the shape, but also amolecular orientation governed by deformation during melting, which isemployed during molding, produces a large effect on the increase incompressive strength. Yet another specific feature of the presentinvention is that molecular orientation can be increased due to a highdeformation ratio and a strong cooling effect.

Means for continuously manufacturing the three-dimensional structure inaccordance with the present invention will be explained below. Amultiplicity of the substrates with the needle-like dies fixed theretoare linked together and fixed to continuously circulating conveyors. Apair of the conveyors are disposed opposite each other, and a resinsheet heated to a temperature equal to or higher than the deflectiontemperature under load is continuously inserted between the pairs ofcontinuously circulating conveyors. The resin sheet is thrust with pairsof needle-like dies by using a mechanism for moving the substrates inthe direction perpendicular to the resin sheet and protrusions areformed on both sides of the resin sheet, thereby continuously molding athree-dimensional structure. With the conventional method in which aresin sheet is directly sandwiched between continuously movingconveyors, because the needles of the needle-like dies in accordancewith the present invention have a large length, they are stick obliquitywhen the resin sheet is sandwiched, and stable molding is impossible. Inaccordance with the present invention, this problem is resolved bymoving the substrates perpendicularly to the resin sheet when the sheetis sandwiched. Various means can be used to implement the verticalmovement of the substrates, and the substrates only may be movedvertically or they may be integrated and moved together with theconveyors. The substrates located on both conveyors or only substrateslocated on one conveyor can be moved vertically.

Examples of the mechanisms for moving the substrates in the verticaldirection when the three-dimensional structure in accordance with thepresent invention is continuously manufactured include two followingmechanisms. One mechanism is means using caterpillars as the conveyorsand moving the substrates perpendicularly to the resin sheet, which isinserted therebetween, by guiding the substrates by the grooves of agrooved cam. Another means comprises pushing up or down only thesubstrates located on the conveyors. Those means are described indetails in description of the preferred embodiment for implementing thepresent invention.

Advantageous Effect of the Invention

The present invention features a three-dimensional structure in whichneedle-like protrusions formed by deforming parts of a resin sheet arepresent on both sides of the resin sheet. Therefore, producing athree-dimensional structure comprising fine needle-like protrusionsmakes it possible to obtain a structure that has characteristics of athree-dimensional structure with pressure resistance, while being athree-dimensional structure with a large cavity. Because a small amountof resin is used, resources are saved, no valuable resources are used invain, and environmental burden during waste treatment is small. Otherperformance features include lightness in weight and high thermalinsulation capability. The bulkiness and lightness in weight of thethree-dimensional structure have been conventionally attained withfoamed bodies, but low surface resistance and poor air and waterpermeability were the drawbacks of foamed bodies. The present inventionprovides a three-dimensional structure that differs in the form thereoffrom foamed bodies, thereby overcoming the aforementioned drawbacks.

Furthermore, because the present invention provides a three-dimensionalstructure which, as described hereinabove, comprises fine needle-likeprotrusions, this structure features flexibility, while having theproperties of a pressure-resistant three-dimensional structure. Goodflexibility makes it possible to wind directly a long product producedin a continuous mode and offers many advantages in terms of productionand usage characteristics at an installation site or the like. Theconventional three-dimensional structures have a large thickness, cannotbe wound, and require extra processes such as cutting. Moreover, becausethey are used in various dimensions, the amount of wasted material islarge. Flexibility as referred to herein is a relative property andmeans that a structure can be obtained that is relatively flexible incomparison with the conventional three-dimensional structures, even if ahard resin such as hard polyvinyl chloride resin or polycarbonate resinis used. Furthermore, because the present invention provides for a highdeformation ratio during molding and good cooling efficiency, themolecular orientation of the molded product is good and a product with ahigh compressive strength can be obtained. Furthermore, if athree-dimensional structure in accordance with the present invention ismolded from a sheet obtained by kneading titanium oxide demonstrating aphotocatalystic action or active carbon demonstrating deodorizingperformance and molding into a sheet, a product with a large surfacearea is obtained due to a high deformation ratio and the properties ofthe titanium oxide or active carbon can be effectively demonstrated.

Flexibility and pressure resistance of the three-dimensional structurein accordance with the present invention make it possible to use it as apackaging material or cushion material for precision instrument and thelike. It also has properties necessary for packaging materials, such aslightness in weight and resistance to water. Because of air and waterpermeability in the direction of sheet surface and pressure resistancein the direction perpendicular to the surface, the laminates of aplurality of three-dimensional structures in accordance with the presentinvention can be used for water curing materials, filters, drainagematerials, and the like. Furthermore, products obtained by joining anonwoven fabric, a cloth, a net, or film to the tips of the needle-likeprotrusions of the three-dimensional structure in accordance with thepresent invention can be used for partition wall, thermal insulatingmaterial, soft ground reinforcing material for civil engineering, watercuring material, and the like. Moreover, products obtained by fillingthe spaces between the needle-like protrusions in accordance with thepresent invention with a fibrous substance and, if necessary, joiningthe tips of the needle-like protrusion to sheet-like objects can be usedfor thermally insulting boards, filters, sewage treatment sheet, floorsin shed for animal, and human-waste treatment plant.

Because of a large length of needles, the three-dimensional structure inaccordance with the present invention cannot be continuouslymanufactured by continuously sandwiching a resin sheet between diesprovided on a pair of conveyors as in the conventional processes.Accordingly, the present invention provides means for effectivelyproducing a three-dimensional structure with fine long protrusions onboth surfaces in a continuous manner by employing means for moving diesprovided on conveyors in the direction perpendicular to the resin sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of thethree-dimensional structure by the present invention;

FIG. 2 is a side view illustrating some of the needle-like protrusionsshown in FIG. 1;

FIG. 3 is another example of the side view illustrating some of theneedle-like protrusions shown in FIG. 1;

FIG. 4 is a side view illustrating an example in which sheet-likeobjects were joined to the tips of the three-dimensional structure bythe present invention;

FIG. 5 illustrates an example of the method for the manufacture of thethree-dimensional structure in accordance with the present invention andshows some of the manufacturing means in a side view;

FIG. 6 is a side view illustrating schematically a process employing anexample of means for opening holes in the tips of the needle-likeprotrusions in accordance with the present invention;

FIG. 7 is a side view illustrating schematically a process employing anexample of means for joining sheet-like objects to the tips of thethree-dimensional structure by the present invention;

FIG. 8 is a side view of a continuous manufacturing apparatus inaccordance with the present invention;

FIG. 9 is a perspective view of a grooved cam portion shown in FIG. 8;

FIG. 10 is a cross-sectional view of the apparatus shown in FIG. 8;

FIG. 11 is a perspective view of a molding member of the apparatus shownin FIG. 8;

FIG. 12 is a schematic drawing illustrating the molding process relatingto FIG. 8;

FIG. 13 is a side view of another continuous manufacturing apparatus inaccordance with the present invention; and

FIG. 14 is a cross-sectional view of the apparatus shown in FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An example of the present invention will be described below based onembodiments thereof illustrated by the appended drawings. FIG. 1 is aperspective view of part of the three-dimensional structure inaccordance with the present invention, this structure comprising amultiplicity of needle-like protrusions 3 a, 3 b, 3 c, . . . directedupward and a multiplicity of needle-like protrusions 4 a, 4 b, 4 c, . .. directed downward from a resin sheet 2. The upward needle-likeprotrusions 3 a, 3 b, 3 c are arranged with a constant pitch p in thelateral direction, and the rear needle-like protrusions 3 d, 3 e, 3 fare located behind the row comprising the needle-like protrusion 3 a ata constant pitch p therefrom and arranged with a constant pitch p in thelateral direction. The needle-like protrusions 4 a, 4 b, 4 c protrudingdownward are arranged with a constant pitch p in the lateral directionin positions shifted by a pitch p/2 backward and by p/2 in the lateraldirection from the upward needle-like protrusions 3 a, 3 b, 3 c. Therear needle-like protrusions 4 d, 4 e, 4 f are located behind the rowcomprising the needle-like protrusion 4 a at a constant pitch ptherefrom and arranged with a constant pitch p in the lateral direction.

FIG. 2 is a side view showing only the needle-like protrusions 3 a, 3 b,3 c presented in FIG. 1. The needle-like protrusions are shown to have aheight H and a width W at ½ height of the protrusion, those dimensionsbeing shown at the needle-like protrusion 3 a as an example. Thecurvature radius of the tip portion 5 of the protrusions is shown forthe needle-like protrusion 3 b as an example. As shown on an enlargedscale in a circle represented by a dot line, a circle 6 inscribed in thesurface of the tip portion 5 is considered as a curvature circle and theradius R thereof is called a curvature radius. Furthermore, an exampleof the structure in which a tip 7 of the protrusion is sliced out and ahole is opened in the tip of the protrusion is shown at the needle-likeprotrusion 3 c as an example. The hole can be also obtained by meltingand removing the tip end section or by punching a small hole in the tipportion with a needle-like object.

FIG. 3 shows an example in which the tip end portions 8 a, 8 b, 8 c ofthe needle-like protrusions 3 a, 3 b, 3 c are constituted by flatportions 9 a, 9 b, 9 c. This flat configuration enlarges the joiningsurface and increases the joining strength when the three-dimensionalstructure by the present invention is adhesively bonded to anothersheet. This flat portion 9 may have the thickness of the sheet 2, butthe thickness thereof is preferably changed so that this portion isthinner than the sheet 2.

FIG. 4 is a side view illustrating an example in which sheet-likeobjects 11 a and 11 b are joined to the tips of the needle-likeprotrusions of the three-dimensional structure 1 shown in FIG. 1. As aresult of joining the sheet-like objects 11, when the three-dimensionalstructure is compressed, all the needle-like protrusions uniformlyreceive the compression force. Therefore, the compressive strength isgreatly increased. Furthermore, the flexural strength is also increasedsignificantly because the tensile strength and compressive strength ofthe sheet-like objects 11 provide for resistance to bending. Usingnonwoven fabric, net-like objects, or perforated films for thesheet-like object 11 can ensure air and water permeability and make itpossible to provide the structure with functions of a filter or drainagematerial. Filling the internal spaces in the three-dimensional structurewith a fibrous substance 12 can further improve functions thereof as amaterial for filters, drainage, and reaction tanks.

FIG. 5 is a side view showing part of an apparatus illustrating anexample of the method for the manufacture of the three-dimensionalstructure 1 by the present invention. In a substrate 21, needle-likedies 23 a, 23 b, 23 c have threaded portions 25 and are fixed to thesubstrate with nuts 26. The needle-like dies 23 a, 23 b, 23 c are onlysome of the dies; thus a multiplicity of the needle-like dies arearranged with a constant pitch in the lateral direction and longitudinaldirection (as shown in the figure) on the plane of the substrate 21. Aplane of a substrate 22 is disposed on the upper surface of thesubstrate 21, facing the plane thereof and mating therewith, andneedle-like dies 24 a, 24 b, 24 c are fixed to the plane of thesubstrate 22. The mutual arrangement of the needle-like dies 24 a, 24 b,24 c and the needle-like dies of the substrate 21 is such that theformer are disposed in positions shifted by ½ pitch in the lateral andlongitudinal directions. Furthermore, a sheet 2 of a molten resin at atemperature equal to or higher than the deflection temperature underload is introduced between the substrate 21 and substrate 22. Bycontrast with the substrate 21, which is fixed, the substrate 22 canmove in the vertical direction, thereby moving the needle-like dies 23a, 23 b, 23 c and needle-like dies 24 a, 24 b, 24 c, which are parallelthereto, with respect to each other. Such a parallel movement forms theneedle-like protrusions 3 a, 3 b, 3 c, 4 a, 4 b, and 4 c. FIG. 5 shows astate in which the substrate 22 assumed the lowermost position. Afterthe protrusions of a constant surface area are formed in the sheet 2 byone stroke of a vertical movement of the substrate 22, the substrate 22assumes the uppermost position, moves, and the adjacent next row ofneedle-like protrusions of a constant surface are formed by thesubsequent movement of the substrate 22 in the vertical direction. Athree-dimensional structure having a multiplicity of needle-likeprotrusions is continuously formed by repeating such operations offorming protrusions with a constant surface area by vertical strokes ofthe substrate 22. The vertical strokes of the substrate 22 can beimplemented by using a vertical movement induced with an air cylinder orhydraulic cylinder or a vertical movement created by employing a cam.The needle-like protrusions 3 and 4 in accordance with the presentinvention have a high deformation ratio, a large surface area, and ahigh cooling efficiency. Therefore, the productivity is increased.However, holes can be provided in the substrates 21 and 22 and coolingair can be introduced therein for additional increase in coolingefficiency.

FIG. 6 shows means for making holes in the tips of the needle-likeprotrusions of the three-dimensional structure by the present invention.Thus, a set of heating rolls 31 a, 31 b is provided in the advancedirection of the three-dimensional structure 1 having the needle-likeprotrusions 3 a, 3 b, . . . , 4 a, 4 b, . . . on both sides of the resinsheet 2, those rolls are brought into contact with the tips of theneedle-like protrusions 3, 4, the tips of the needle-like protrusions 3,4 are melted and removed, and subsequent cooling with a set of coolingrolls 32 a, 32 b produces a three-dimensional structure 35 having holes33 a, 33 b, . . . , 34 a, 34 b in the tips. A heating conveyor, hot-airflow, or torches can be used in place of the heating rollers 31, but inall the cases the temperature is preferably 30-50° C. higher than themelting point (in the case of amorphous polymers, the secondarytransition temperature) of the resin sheet, and a high temperature whichis at least 100° C. higher than the melting point is especiallypreferred.

FIG. 7 shows means for joining the sheet-like objects to thethree-dimensional structure 1 by the present invention. Thus, a set ofheating rolls 41 a, 41 b is provided in the advance direction of thethree-dimensional structure 1 having the needle-like protrusions 3 a, 3b, . . . , 4 a, 4 b on both sides of the resin sheet 2, the sheet-likeobjects 42 a, 42 b are guided to those rolls, heated with the heatingrolls 41, softened, brought into contact with the tips of needle-likeprotrusions 3, 4, and joined to the tips of the needle-like protrusions3, 4, thereby producing a three-dimensional structure 43 joined to thesheet-like objects. The heating rolls 41 are not required to be heatedto a very high temperature, by contrast with the heating rolls 31 shownin FIG. 6, but they have to provide the sheet-like objects 42 with heatsufficient for joining. Furthermore, when the sheet-like objects 42 arethe molten resin sheets released from T dies, the rolls rather have tobe at a temperature such that the molten resin is cooled. In the casewhere the sheet-like objects 42 change their properties under heating,as microporous films or nonwoven fabrics, or when they are difficult tojoin by heating alone, as knitted products or nets, the temperature ofthe heating rolls is difficult to increase. Therefore, adhesive webs 44a, 44 b can be introduced between the three-dimensional structure 1 andsheet-like objects 42 and adhesive boding can be implemented with theadhesive webs 44. When the sheet-like objects 42 feature good air andwater permeability, like microporous films and nonwoven fabrics, theadhesive web 44 is preferred to be in the form of nonwoven fabric or anet-like object so that the air permeability thereof is not lost.Furthermore, when air permeability of the adhesive webs 44 is low,joining is preferably conducted by disposing the adhesive webs 44locally in the form of stripes, rather than on the entire surface of thesheet-like objects 42. Furthermore, a three-dimensional structure 43with sheet-like objects joined thereto can be also manufactured byapplying an adhesive to the joining surface of the sheet-like objects 42or the tips of the needle-like protrusions 3, 4 of the three-dimensionalstructure 1, without using the adhesive webs 44.

FIGS. 8 to 12 illustrate examples of continuous manufacture of thethree-dimensional structure in accordance with the present invention.FIG. 8 is a side view of the entire apparatus. A caterpillar 64 a isused as a conveyor continuously circulating between the rolls 60, 61,and a caterpillar 64 b facing the caterpillar 64 a circulates betweenthe rollers 62, 63. The caterpillars 64 have a multiplicity of verticalpins 74 projecting therefrom with a fixed spacing (only some of them areshown in the figure). The caterpillars are produced by using multiplesubstrates 70 having multiple needle-like protrusions (not shown in thefigure) on the surface shown in FIG. 5, forming openings in thesubstrates, and inserting and fixing the vertical pins 74. A resin sheet80 serving as a starting material is molded with part of a grooved cam65 and becomes the three-dimensional structure 81.

FIGS. 9 and 10 are perspective views of components of the manufacturingapparatus by the present invention. FIG. 9 shows the grooved cam 65 andillustrates a state in which guide grooves 66, 67 for substrates andguide grooves 68, 69 for parting plates are formed in a plate. FIG. 10shows the caterpillar 64, vertical pins 74 standing thereon, a substrate70 provided with a plurality of needle-like dies 71, a parting plate 72having through holes 73 for needle-like dies, those holes correspondingto the needle-like dies 71, pins 75 for substrates that are provided onthe side surface of the substrate 70, and pins 76 for parting that areprovided on the side surface of the parting plate 72. When the pins 75for the substrate and pins 76 for the parting plate are guided byrespective grooves of the grooved cam 65 shown in FIG. 9, the substrates70 provided on the upper and lower caterpillars 64 a, 64 b move in thedirection perpendicular to the resin sheet 80 (parallel to the upper andlower needles) and pass through the resin sheet 80, thereby forming thethree-dimensional structure 81. In the course of separation after theapproach, the upper and lower guide grooves 66, 67 for substrates andthe guide grooves 68, 69 for parting plates shown in FIG. 9 provide fora path different from that in the case of approach in order tofacilitate the separation of the molded three-dimensional structure 81from the needle-like dies of the substrate.

FIG. 11 is a cross-sectional view from the front surface illustratingthe entire apparatus shown in FIG. 8. This view illustrates thearrangement of the grooved cam 65, caterpillars 64, vertical pins 74standing thereon, substrate 70 provided with multiple needle-like dies71, parting plates 72, pins 75 for substrate that are provided on theside surface of the substrate 70, and pins 76 for separation that areprovided on the side surface of the parting plate 72.

FIG. 12 shows a portion of the grooved cam 65 of the entire structuraldrawing of the apparatus shown in FIG. 8 and illustrates how theneedle-like dies 71 provided in a vertical condition on the substrate 70and the parting plate 72 acts on the resin sheet 80 serving as astarting material. In step A, in the inlet portion of the grooved cam65, both the needle-like dies 71 attached to the substrate 70 and theparting plates 72 are separated from the resin sheet 80. In step B, thelower and upper needle-like dies 71 move perpendicularly to the resinsheet 80 and thrust the resin sheet 80. In step C, first, theneedle-like dies 71 are separated from the molded three-dimensionalstructure 81, but the parting plate 72 still remains on the side of themolded three-dimensional structure 81. In step D, the parting plate 72is also separated from the three-dimensional structure 81. Such aperpendicular movement of the substrate 70 and parting plate 72 withrespect to the resin sheet is carried out along the trajectories of theguide grooves 66, 67 for substrates and guide grooves 68, 69 for partingplates provided in the grooved cam 65.

FIGS. 13 and 14 illustrate another means for continuously molding thesheet-like objects of the three-dimensional structure 1 by the presentinvention. FIG. 13 is a side view taken from the lateral direction ofthe apparatus, and FIG. 14 shows A-A and B-B cross-sectional views ofthe structure shown in FIG. 13. A conveyor 103 circulates between therolls 101, 102. Multiple pins 104 a, 104 b (only some of them are shownin the figure to facilitate understanding) are provided in a verticalcondition with a constant spacing on both end sections of the conveyor103. Substrates 105 a, 105 b having multiple needle-like protrusions(not shown in the figure) on the surface shown in FIG. 5 have holes onboth end portions thereof and are fixed to the pins 104 of the conveyor103 via those holes. The conveyor 103 is preferably magnetized with amagnetic rubber, magnetic plastic, or other means having magnetsembedded therein, and the substrates 105 are fixed to the conveyor 103by using magnetic properties of the conveyor 73. When the conveyor 103and a conveyor 106 forming in the lower part thereof a pair with theconveyor 103 and circulating at the same speed come close to each other,while facing each other, the substrates 105 are separated from thesurface of the conveyor 103 by the rising slope of a stand 110 sloped inthe front and rear sections thereof and the substrates move gradually upalong the pins 104 in the direction perpendicular to the direction ofthe resin sheet 2 serving as a starting material. Then, after passingthrough the section where they move parallel to the conveyor 103, thesubstrates are again caused to move to the conveyor 103 by the decliningslope of the stand 110.

The conveyor 106 forming a pair with the conveyor 103 circulates at thesame speed as the conveyor 103 between the rolls 107, 108 and similarlyhas multiple pins 111 a, 111 b and multiple substrates 112 a, 112 bfixed thereto. The pins 111 and substrates 112 of the conveyor 106circulating in pair with the conveyor 103 are similarly pushed up by thestand 113 and move perpendicularly to the resin sheet 2. As a result ofsuch perpendicular movement of the substrate 105 and substrates 112, theneedles of the needle-like protrusions (not shown in the figures)provided on the substrates 105, 112 move parallel to each other via theresin sheet 2 traveling between the substrates, the needles thrust theresin sheet 2, and a sheet 114 having needle-like protrusions on bothsurfaces of the resin sheet 2 is obtained. In the figure, a thermostator a heating unit for the resin sheet 2, which is to be inserted, arenot shown. Furthermore, a cooling unit for the resin sheet subjected topiercing with the needle-like protrusion of the substrate is also notshown. FIG. 10 shows an example in which the substrates 105, 112 of thetwo groups moved vertically, but vertical movement may be performed onlyby one group, for example, by substrates 112.

FIG. 14A is a sectional view along A-A in FIG. 13, and FIG. 14B is asectional view along B-B. The two figures illustrate only the upper partof the apparatus shown in FIG. 13. The stand 110 is disposed on theoutside of the conveyor 113. A guide rail can be provided on theconveyor 103 on the opposite side from the stand 110 shown in FIG. 13 soas to push down the substrates 105 when the substrates 115 return to theconveyor 103. In order to reduce friction, the stand and guide railpreferably comprise small rollers or bearings. Furthermore, materialswith a low friction coefficient or a lubricant can be used.

EXAMPLE 1

High-density polyethylene (manufactured by Japan Polyolefin Co., Ltd.,J-REX□HD, KL371A, MFR 1.0, density 0.956 g/cm3, deflection temperatureunder load 65° C.) was used as a starting material resin. This resin wasextrusion molded at 275° C. from a T die, and guided to athree-dimensional structure molding process shown in FIG. 5, so as toobtain a sheet with a thickness of 300 μm in a molded state. Two sets ofmolds combining four commercial pinholders for IKEBANA (flowerarrangement) were used as the substrates 21, 22 and needle-like dies 22,23 shown in FIG. 5. The diameter of the needle-like dies of thepinholders was 1.35 mm, the pitch was 3.7 mm, and the height was 13 mm.Those two molds were set so that the tips thereof faced each other, amolten resin sheet molded from a T die was sandwiched between the molds,and the needle-like dies were engaged so as to thrust the resin sheet.The temperature of the molten resin sheet at this time was 232° C. Amolding cooled by the air and thermal capacity of the needle-like dieswas removed from the molds and the three-dimensional structure shown inFIG. 1 was obtained. The height H of the three-dimensional structure was5.1 mm, the width W at ½ H was 1.5 mm, and the pitch between adjacentneedle-like protrusions was 3.7 mm.

INDUSTRIAL APPLICABILITY

The three-dimensional structure in accordance with the present inventionexcels in pressure resistance, despite being flexible, and has goodwater permeability and thermal insulating properties. It is suitable forbuffer sheets, cushion sheets, partition wall, and floors.

1. (canceled)
 2. (canceled)
 3. (canceled)
 4. (canceled)
 5. (canceled) 6.(canceled)
 7. (canceled)
 8. A method for the manufacture of athree-dimensional structure, wherein a multiplicity of needle-like diesare provided so as to be integrated with a substrate, a multiplicity ofsaid substrates are linked together and fixed to continuouslycirculating conveyors, a pair of the conveyors travels opposing eachother so that a pair of said substrates travel opposing each other, aresin sheet heated to a temperature equal to or higher than thedeflection temperature under load is continuously inserted between saidpair of continuously circulating conveyors, said pair of substrates arevertically moved with respect to said resin sheet, and needle-likeprotrusions are continuously formed on both sides of said resin sheet bycausing said pairs of needle-like dies to thrust said resin sheet,wherein: said conveyors comprise caterpillars, said substrates are fixedto vertical pins standing on said caterpillars, and said verticalmovement is carried out by guiding the substrate support pins providedon the side surface of said substrate with a grooved cam; and separationplate support pins provided on the side surface of separation plateshaving holes on positions corresponding to said needle-like diesprotrusions on each surface of said pair of substrates are guided by agrooved cam on a track other than said substrate, and said substratesand the molded resin sheet are continuously separated by said separationplates.
 9. (canceled)
 10. An apparatus for the manufacture of athree-dimensional structure, wherein a multiplicity of needle-like diesare provided so as to be integrated with a substrate, a multiplicity ofsaid substrates are linked together and fixed to continuouslycirculating conveyors, a pair of the conveyors are disposed such thatthey travel opposing each other so that a pair of substrates travelopposing each other, a resin sheet heated to a temperature equal to orhigher than the deflection temperature under load is formed so as to becontinuously inserted between said pair of continuously circulatingconveyors, and using a mechanism in which the pair of substrates arevertically moved with respect to the resin sheet, needle-likeprotrusions are continuously formed on both sides of said resin sheet bycausing said pairs of needle-like dies to thrust said resin sheet,wherein: said conveyors comprise caterpillars, said substrates are fixedto vertical pins standing on said caterpillars, and said verticalmovement is carried out by guiding the substrate support pins providedon the side surface of said substrate with a grooved cam; and there areprovided separation plates having holes on positions corresponding tosaid needle-like dies protrusions on each surface of said pair ofsubstrates, separation plate support pins provided on the side surfaceof said separation plates are guided by a grooved cam on a track otherthan said substrate, and said substrates and the molded resin sheet arecontinuously separated.
 11. (canceled)
 12. An apparatus for themanufacture of a three-dimensional structure, wherein a multiplicity ofneedle-like dies are provided so as to be integrated with a substrate, amultiplicity of said substrates are linked together and fixed tocontinuously circulating conveyors, a pair of the conveyors are disposedso as to travel opposing each other so that a pair of said substratestravel opposing each other, a resin sheet heated to a temperature equalto or higher than the deflection temperature under load is formed so asto be continuously inserted between said pair of continuouslycirculating conveyors, and using a mechanism in which the pair ofsubstrates are vertically moved with respect to the resin sheet,needle-like protrusions are continuously formed on both sides of saidresin sheet by causing said pairs of needle-like dies to thrust saidresin sheet, wherein: pins are vertically provided on said conveyors,said substrate is fixed on said conveyors by the pins piercing holesprovided on said substrate, and said vertical movement of said substrateis carried out by mounts provided on both sides of said conveyor; andthere are provided separation plates having holes on positionscorresponding to said needle-like dies protrusions on each surface ofsaid pair of substrates, said separation plates are guided by a mountwith a track other than said substrate, and said substrates and themolded resin sheet are continuously separated.